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by Dennis Overbye
March 14, 2018
from
NYTimes Website
Spanish version
Stephen Hawking became a leader
in
exploring gravity and the properties of black holes.
His
work led to a turning point in the history of modern physics.
Credit
Terry Smith/Time Life Pictures, via Getty Images
A physicist and best-selling
author, Dr. Hawking did not
allow his physical limitations to hinder his quest to answer
"the big question: Where did the universe come from?"
Stephen W. Hawking, the Cambridge University physicist and
best-selling author who roamed the cosmos from a wheelchair,
pondering the nature of gravity and the origin of the universe and
becoming an emblem of human determination and curiosity, died early
Wednesday at his home in Cambridge, England.
He was 76.
A university spokesman confirmed the death.
"Not since Albert
Einstein has a scientist so captured the public imagination and
endeared himself to tens of millions of people around the
world," Michio Kaku, a professor of theoretical physics at the
City University of New York, said in an interview.
Dr. Hawking did that
largely through his book "A Brief History of Time - From the Big
Bang to Black Holes," published in 1988. It has sold more than 10
million copies and inspired a documentary film by Errol Morris.
His own story was the
basis of an award-winning 2014 feature film, "The Theory of
Everything." (Eddie Redmayne played Dr. Hawking and won an Academy
Award.)
Stephen Hawking,
one of
the greatest physicists of our time,
died on
Wednesday.
He is
immortalized by his brilliant research,
but
also by his pop culture appearances.
By
CAMILLA SCHICK on Publish Date March 14, 2018.
Photo
by David Parry/Press Association,
via
Associated Press.
Scientifically, Dr. Hawking will be best remembered for a discovery
so strange that it might be expressed in the form of a Zen koan:
When is a black hole
not black? When it explodes.
What is equally amazing
is that he had a career at all.
As a graduate student in
1963, he learned he had amyotrophic lateral sclerosis, a
neuromuscular wasting disease also known as Lou Gehrig's disease.
He was given only a few
years to live...
The disease reduced his bodily control to the flexing of a finger
and voluntary eye movements but left his mental faculties untouched.
He went on to become his generation's leader in exploring gravity
and the
properties of black holes, the bottomless gravitational pits
so deep and dense that not even light can escape them.
That work led to a turning point in modern physics, playing itself
out in the closing months of 1973 on the walls of his brain when Dr.
Hawking set out to apply quantum theory, the weird laws that govern
subatomic reality, to black holes.
In a long and daunting
calculation, Dr. Hawking discovered to his befuddlement that black
holes - those mythological avatars of cosmic doom - were not really
black at all.
In fact, he found, they
would eventually fizzle, leaking radiation and particles, and
finally explode and disappear over the eons.
SLIDE SHOW
- Click above image
The Expansive Life of Stephen Hawking
Credit Paul E. Alers/NASA
Nobody, including Dr. Hawking, believed it at first - that particles
could be coming out of a black hole.
"I wasn't looking for
them at all," he recalled in 1978. "I merely tripped over them.
I was rather annoyed."
That calculation, in a
thesis published in 1974 in the journal Nature under the title
"Black Hole Explosions?," is hailed by scientists as the first great
landmark in the struggle to find a single theory of nature - to
connect gravity and quantum mechanics, those warring descriptions of
the large and the small, to explain a universe that seems stranger
than anybody had thought.
The discovery of
Hawking radiation, as it is known, turned black
holes upside down.
It transformed them from destroyers to creators -
or at least to recyclers - and wrenched the dream of a final theory
in a strange, new direction.
"You can ask what
will happen to someone who jumps into a black hole," Dr. Hawking
said in 1978. "I certainly don't think he will survive it."
"On the other hand," he added, "if we send someone off to jump
into a black hole, neither he nor his constituent atoms will
come back, but his mass energy will come back.
Maybe that
applies to the whole universe."
Dennis W. Sciama,
a cosmologist and Dr. Hawking's thesis adviser at Cambridge, called
Hawking's thesis in Nature,
"the most beautiful
paper in the history of physics."
Edward Witten, a
theorist at the Institute for Advanced Study in Princeton, said:
"Trying to understand
Hawking's discovery better has been a source of much fresh
thinking for almost 40 years now, and we are probably still far
from fully coming to grips with it. It still feels new."
In 2002, Dr. Hawking said
he wanted the formula for Hawking radiation to be engraved on his
tombstone.
He was a man who pushed the limits - in his intellectual life, to be
sure, but also in his professional and personal lives.
-
traveled the
globe to scientific meetings, visiting every continent,
including Antarctica
-
wrote
best-selling books about his work
-
married twice
-
fathered three
children
-
was not above
appearing on "The Simpsons," "Star Trek: The Next
Generation" or "The Big Bang Theory"
He celebrated his 60th
birthday by going up in a hot-air balloon.
The same week, he also
crashed his electric-powered wheelchair while speeding around a
corner in Cambridge, breaking his leg.
In April 2007, a few months after his 65th birthday, he
took part in a zero-gravity flight aboard a specially equipped
Boeing 727, a padded aircraft that flies a roller-coaster trajectory
to produce fleeting periods of weightlessness.
It was a prelude to a
hoped-for trip to space with Richard Branson's Virgin
Galactic company aboard
SpaceShipTwo.
Asked why he took such risks, Dr. Hawking said,
"I want to show that
people need not be limited by physical handicaps as long as they
are not disabled in spirit."
Dr. Hawking
pushed
the limits in his professional and personal life.
At 65,
he took part in a zero-gravity flight
aboard
a plane that flies a roller-coaster trajectory
to
produce fleeting periods of weightlessness.
Credit
Steve Boxall/Zero Gravity Corporation
His own spirit left many in awe.
"What a triumph his
life has been," said Martin Rees, a Cambridge University
cosmologist, the astronomer royal of England and Dr. Hawking's
longtime colleague.
"His name will live
in the annals of science; millions have had their cosmic
horizons widened by his best-selling books; and even more,
around the world, have been inspired by a unique example of
achievement against all the odds - a manifestation of amazing
willpower and determination."
Studies Came
Easy
Stephen William Hawking was born in Oxford, England, on Jan.
8, 1942 - 300 years to the day, he liked to point out, after the
death of Galileo, who had begun the study of gravity.
His mother, the former
Isobel Walker, had gone to Oxford to avoid the bombs that fell
nightly during the Blitz of London.
His father, Frank
Hawking, was a prominent research biologist.
The oldest of four children, Stephen was a mediocre student at St.
Albans School in London, though his innate brilliance was recognized
by some classmates and teachers.
Later, at University College, Oxford, he found his studies in
mathematics and physics so easy that he rarely consulted a book or
took notes. He got by with a thousand hours of work in three years,
or one hour a day, he estimated.
"Nothing seemed worth
making an effort for," he said.
The only subject he found
exciting was cosmology because, he said, it dealt with,
"the big question:
Where did the universe come from?"
He moved to Cambridge
upon his graduation from Oxford.
Before he could begin his
research, however, he was stricken by what his research adviser, Dr.
Sciama, came to call "that terrible thing."
The young Hawking had been experiencing occasional weakness and
falling spells for several years. Shortly after his 21st birthday,
in 1963, doctors told him that he had amyotrophic lateral sclerosis.
They gave him less than three years to live...
His first response was severe depression. He dreamed he was going to
be executed, he said.
Then, against all odds,
the disease appeared to stabilize. Though he was slowly losing
control of his muscles, he was still able to walk short distances
and perform simple tasks, though laboriously, like dressing and
undressing.
He felt a new sense of
purpose.
"When you are faced
with the possibility of an early death," he recalled, "it makes
you realize that life is worth living and that there are a lot
of things you want to do."
In 1965, he married
Jane Wilde, a student of linguistics.
Now, by his own account,
he not only had "something to live for"; he also had to find a job,
which gave him an incentive to work seriously toward his doctorate.
His illness, however, had robbed him of the ability to write down
the long chains of equations that are the tools of the cosmologist's
trade.
Characteristically, he
turned this handicap into a strength, gathering his energies for
daring leaps of thought, which, in his later years, he often left
for others to codify in proper mathematical language.
Dr. Hawking
and his first wife,
the former Jane
Wilde, in 1990.
The couple married in
1965.
He said the marriage
gave him "something to live for."
Credit David
Montgomery/Getty Images
"People have the
mistaken impression that mathematics is just equations," Dr.
Hawking said. "In fact, equations are just the boring part of
mathematics."
By necessity, he
concentrated on problems that could be attacked through "pictures
and diagrams," adopting geometric techniques that had been devised
in the early 1960s by the mathematician Roger Penrose and a
fellow Cambridge colleague, Brandon Carter, to study general
relativity, Einstein's theory of gravity.
Black holes are a natural prediction of that theory, which explains
how mass and energy "curve" space, the way a sleeping person causes
a mattress to sag.
Light rays will bend as
they traverse a gravitational field, just as a marble rolling on the
sagging mattress will follow an arc around the sleeper.
Too much mass or energy in one spot could cause space to sag without
end; an object that was dense enough, like a massive collapsing
star, could wrap space around itself like a magician's cloak and
disappear, shrinking inside to a point of infinite density called
a
singularity, a cosmic dead end, where the known laws of physics
would break down:
a
black hole.
Einstein himself thought this was absurd when the possibility was
pointed out to him.
Dr. Hawking in his office
at the
University of Cambridge in December 2011.
His
only complaint about his speech synthesizer,
which
was manufactured in California,
was
that it gave him an American accent.
Credit
Sarah Lee/London Science Museum,
via
Agence France-Presse - Getty Images
Using the
Hubble Space Telescope and other sophisticated tools of
observation and analysis, however, astronomers have identified
hundreds of objects that are too massive and dark to be anything but
black holes, including a
supermassive one at the center of the Milky
Way.
According to current
theory, the universe should contain billions more.
As part of his Ph.D. thesis in 1966, Dr. Hawking showed that when
you ran the film of the expanding universe backward, you would find
that such a singularity had to have existed sometime in cosmic
history; space and time, that is, must have had a beginning.
He, Dr. Penrose and a
rotating cast of colleagues published a series of theorems about the
behavior of black holes and the dire fate of anything caught in
them.
A Calculation in His
Head
Dr. Hawking's signature breakthrough resulted from a feud with the
Israeli theoretical physicist Jacob Bekenstein, then a
Princeton graduate student, about whether black holes could be said
to have entropy, a thermodynamic measure of disorder.
Dr. Bekenstein said they
could, pointing out a close analogy between the laws that Dr.
Hawking and his colleagues had derived for black holes and the
laws
of thermodynamics.
Dr. Hawking said no. To have entropy, a black hole would have to
have a temperature. But warm objects, from a forehead to a star,
radiate a mixture of electromagnetic radiation, depending on their
exact temperatures.
Nothing could escape a
black hole, and so its temperature had to be zero.
"I was very down on
Bekenstein," Dr. Hawking recalled.
Dr. Hawking in 1979.
The
only subject at University College, Oxford,
that he
found exciting was cosmology because
it
dealt with what he called
"the
big question: Where did the universe come from?"
Credit
Santi Visalli/Getty Images
To settle the question, Dr. Hawking decided to investigate the
properties of
atom-size black holes.
This, however, required
adding
quantum mechanics, the paradoxical rules of the atomic and
subatomic world, to gravity, a feat that had never been
accomplished. Friends turned the pages of quantum theory textbooks
as Dr. Hawking sat motionless staring at them for months.
They wondered if he was
finally in over his head.
When he eventually succeeded in doing the calculation in his head,
it indicated to his surprise that particles and radiation were
spewing out of black holes. Dr. Hawking became convinced that his
calculation was correct when he realized that the outgoing radiation
would have a thermal spectrum characteristic of the heat radiated by
any warm body, from a star to a fevered forehead.
Dr. Bekenstein had
been right.
Dr. Hawking even figured out a way to explain how particles might
escape a black hole.
According to quantum
principles, the space near a black hole would be teeming with
"virtual" particles that would flash into existence in matched
particle-and-antiparticle pairs - like electrons and their evil twin
opposites, positrons - out of energy borrowed from the hole's
intense gravitational field.
They would then meet and annihilate each other in a flash of energy,
repaying the debt for their brief existence.
But if one of the pair
fell into the black hole, the other one would be free to wander away
and become real. It would appear to be coming from the black hole
and taking energy away from it.
But those, he cautioned, were just words. The truth was in the math.
"The most important
thing about Hawking radiation is that it shows that the black
hole is not cut off from the rest of the universe," Dr. Hawking
said.
It also meant that black
holes had a temperature and had
entropy.
In thermodynamics,
entropy is a measure of wasted heat. But it is also a measure of the
amount of information - the number of bits - needed to describe what
is in a black hole.
Curiously, the number of
bits is proportional to the black hole's surface area, not its
volume, meaning that the amount of information you could stuff into
a black hole is limited by its area, not, as one might think, its
volume.
That result has become a
litmus test for string theory and other
pretenders to a theory of quantum gravity. It has also led to
speculations that we live in
a holographic universe, in which
three-dimensional space is some kind of illusion.
Andrew Strominger, a Harvard string theorist, said of the
holographic theory,
"If it's really true,
it's a deep and beautiful property of our universe - but not an
obvious one."
To 'Know the
Mind of God'
The discovery of black hole radiation also led to a 30-year
controversy over the fate of things that had fallen into a black
hole.
Dr. Hawking initially said that detailed information about whatever
had fallen in would be lost forever because the particles coming out
would be completely random, erasing whatever patterns had been
present when they first fell in.
Paraphrasing Einstein's
complaint about the randomness inherent in quantum mechanics, Dr.
Hawking said,
"God not only plays
dice with the universe, but sometimes throws them where they
can't be seen."
Many particle physicists
protested that this violated a tenet of quantum physics, which says
that knowledge is always preserved and can be retrieved.
Leonard Susskind,
a Stanford physicist who carried on the argument for decades, said,
"Stephen correctly
understood that if this was true, it would lead to the downfall
of much of 20th-century physics."
On another occasion, he
characterized Dr. Hawking to his face as,
"one of the most
obstinate people in the world; no, he is the most infuriating
person in the universe." Dr. Hawking grinned.
Dr. Hawking admitted
defeat in 2004. Whatever information goes into a black hole will
come back out when it explodes.
One consequence, he noted
sadly, was that one could not use black holes to escape to another
universe.
"I'm sorry to
disappoint science fiction fans," he said.
Despite his concession,
however, the information paradox, as it is known, has become one of
the hottest topics in theoretical physics. Physicists say they still
do not know how information gets in or out of black holes.
Raphael Bousso of the University of California, Berkeley, and
a former student of Dr. Hawking's, said the present debate had
raised,
"by another few
notches" his estimation of the "stupendous magnitude" of Dr.
Hawking's original discovery.
In 1974, Dr. Hawking was
elected a Fellow of the Royal Society, the world's oldest
scientific organization; in 1979, he was appointed to the
Lucasian chair of mathematics at Cambridge, a post once held by
Isaac Newton.
"They say it's
Newton's chair, but obviously it's been changed," he liked to
quip.
Dr. Hawking also made
yearly visits to the California Institute of Technology in Pasadena,
which became like a second home.
In 2008, he joined the
Perimeter Institute for Theoretical Physics in Waterloo, Ontario, as
a visiting researcher.
Having conquered black holes, Dr. Hawking set his sights on the
origin of the universe and on eliminating that pesky singularity at
the beginning of time from models of cosmology.
If the laws of physics
could break down there, they could break down everywhere.
In a meeting at the Vatican in 1982, he suggested that in the final
theory there should be no place or time when the laws broke down,
even at the beginning. He called the notion the "no boundary"
proposal.
With James Hartle of the Institute for Theoretical Physics in
Santa Barbara, Calif., Dr. Hawking envisioned the history of the
universe as a sphere like the Earth. Cosmic time corresponds to
latitude, starting with zero at the North Pole and progressing
southward.
Although time started there, the North Pole was nothing special; the
same laws applied there as everywhere else.
Asking what happened
before the Big Bang, Dr. Hawking said, was like asking what was a
mile north of the North Pole - it was not any place, or any time.
By then,
string theory, which claimed finally to explain both
gravity and the other forces and particles of nature as tiny
microscopically vibrating strings, like notes on a violin, was the
leading candidate for a "theory of everything."
In "A Brief History of Time," Dr. Hawking concluded that,
"if we do discover a
complete theory" of the universe, "it should in time be
understandable in broad principle by everyone, not just a few
scientists."
He added,
"Then we shall all,
philosophers, scientists and just ordinary people, be able to
take part in the discussion of why it is that we and the
universe exist."
"If we find the answer to that," he continued, "it would be the
ultimate triumph of human reason - for then we would know the
mind of God."
"I want to show that
people need not be
limited by physical
handicaps as long as they
are not disabled in spirit."
Dr.
Hawking
Until 1974, Dr. Hawking was still able to feed himself and to get in
and out of bed.
At Jane's insistence, he
would drag himself, hand over hand, up the stairs to the bedroom in
his Cambridge home every night, in an effort to preserve his
remaining muscle tone.
After 1980, care was supplemented by nurses.
Dr. Hawking retained some control over his speech up to 1985. But on
a trip to Switzerland, he came down with pneumonia. The doctors
asked Jane if she wanted his life support turned off, but she said
no.
To save his life, doctors
inserted a breathing tube. He survived, but his voice was
permanently silenced.
Speaking With
the Eyes
It appeared for a time that he would be able to communicate only by
pointing at letters on an alphabet board.
But when a computer
expert, Walter Woltosz, heard about Dr. Hawking's condition,
he offered him a program he had written called
Equalizer.
By
clicking a switch with his still-functioning fingers, Dr. Hawking
was able to browse through menus that contained all the letters and
more than 2,500 words.
Word by word - and when necessary, letter by letter - he could build
up sentences on the computer screen and send them to a speech
synthesizer that vocalized for him.
The entire apparatus was
fitted to his motorized wheelchair.
Even when too weak to move a finger, he communicated through the
computer by way of an infrared beam, which he activated by twitching
his right cheek or blinking his eye. The system was expanded to
allow him to open and close the doors in his office and to use the
telephone and internet without aid.
Although he averaged fewer than 15 words per minute, Dr. Hawking
found he could speak through the computer better than he had before
losing his voice.
His only complaint, he
confided, was that the speech synthesizer, manufactured in
California, gave him a new vocal inflection.
"Please pardon my
American accent," he used to say.
His decision to write "A
Brief History of Time" was prompted, he said, by a desire to share
his excitement about,
"the discoveries that
have been made about the universe" with "the public that paid
for the research."
He wanted to make the
ideas so accessible that the book would be sold in airports.
He also hoped to earn enough to pay for his children's education. He
did. The book's extraordinary success made him wealthy, a hero to
disabled people everywhere and even more famous.
The news media followed his movements and activities over the years,
from visiting the White House to meeting the Dallas Cowboys
cheerleaders, and reported his opinions on everything from national
health care (socialized medicine in England had kept him alive) to
communicating with extraterrestrials (maybe not a good idea, he
said), as if he were a rolling Delphic Oracle.
Asked by New Scientist magazine what he thought about most, Dr.
Hawking answered:
"Women. They are a
complete mystery."
The Academy Award-winning director James Marsh
discusses his newest project, "The Theory of Everything,"
which chronicles the life of the cosmologist Stephen Hawking.
By Carrie Halperin on Publish Date October 27, 2014.
Photo by Liam Daniel/Focus Features.
In 1990, Dr. Hawking and his wife separated after 25 years of
marriage; Jane Hawking wrote about their years together in two
books,
The latter became the
basis of the movie "The Theory of Everything."
In 1995, he married Elaine Mason, a nurse who had cared for
him since his bout of pneumonia. She had been married to David
Mason, the engineer who had attached Dr. Hawking's speech
synthesizer to his wheelchair.
In 2004, British newspapers reported that the Cambridge police were
investigating allegations that Elaine had abused Dr. Hawking, but no
charges were filed, and Dr. Hawking denied the accusations.
They later divorced...
Dr. Hawking married Elaine Mason in 1995.
Credit
Lynne Sladky/Associated Press
His survivors include his children, Robert, Lucy and Tim, and three
grandchildren.
'There Is No
Heaven'
Among his many honors, Dr. Hawking was named a commander of the
British Empire in 1982. In the summer of 2012, he had a star role in
the opening of the Paralympics Games in London.
The only thing lacking
was the Nobel Prize, and his explanation for this was
characteristically pithy:
"The Nobel is given
only for theoretical work that has been confirmed by
observation. It is very, very difficult to observe the things I
have worked on."
Dr. Hawking was a strong
advocate of space exploration, saying it was essential to the
long-term survival of the human race.
"Life on Earth is at
the ever-increasing risk of being wiped out by a disaster, such
as sudden global nuclear war, a genetically engineered virus or
other dangers we have not yet thought of," he told an audience
in Hong Kong in 2007.
Nothing raised as much
furor, however, as his increasingly scathing remarks
about religion.
One attraction of the
no-boundary proposal for Dr. Hawking was that there was no need to
appeal to anything outside the universe, like God, to explain how it
began.
In "A Brief History of Time," he had referred to the "mind of God,"
but in "The Grand Design," a 2011 book he wrote with Leonard
Mlodinow, he was more bleak about religion.
"It is not necessary
to invoke God to light the blue touch paper," he wrote,
referring to the British term for a firecracker fuse, "and set
the universe going."
He went further that
year,
telling The Guardian:
"I regard the brain
as a computer which will stop working when its components fail.
There is no heaven or afterlife for broken-down computers; that
is a fairy story for people afraid of the dark."
Dr. Hawking saw space exploration
as
essential to the long-term survival of the human race.
"Life on Earth is at the ever-increasing risk
of being wiped out by a disaster,
such as sudden global nuclear war," he said in 2007.
Credit David Silverman/Getty Images
Having spent the best part of his life grappling with black holes
and cosmic doom, Dr. Hawking had no fear of the dark.
"They're named black
holes because they are related to human fears of being destroyed
or gobbled up," he once told an interviewer.
"I don't have fears
of being thrown into them. I understand them. I feel in a sense
that I am their master."
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